By utilizing a group contribution method (GCM) by specifying the number of functional
groups forming the molecules, estimation of some of the pivotal properties of substances
becomes feasible. To broaden the scope of the predictable properties and to expand
the applicability of the GCM procedure, it may be required to combine it with an equation
of state. In this work, the internal energy, enthalpy, and entropy in 2000 states
per material of 69 compounds from the NIST database were compared with the results
of 25 different GCM-based cubic equations of state and analyzed by classes of compounds
to identify the limitations of the method and to suggest the use of an equation of
state for each type of compounds.
Interestingly, equations that depend on fewer material properties tend to yield better
results, especially when those properties can be estimated with high precision. In
contrast, equations that rely on more parameters may be more sensitive to inaccuracies
in property estimates, making them less reliable.
